ElasticSearch 查询DSL
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查询DSL
在Elasticsearch中，搜索是通过使用基于JSON的查询来进行的。查询由两个子句组成-- 叶子查询子句 - 这些子句是匹配项，术语或范围，它们在特定字段中寻找特定值。
- 复合查询子句 - 这些查询是叶查询子句和其他复合查询的组合，以提取所需的信息。
Elasticsearch支持大量查询。查询以查询关键字开头，然后以JSON对象的形式包含条件和过滤器。下面描述了不同类型的查询。 -
匹配所有查询
这是最基本的查询；它返回所有内容，每个对象的得分为1.0。POST /school/_search { "query":{ "match_all":{} } }运行上面的代码，我们得到以下结果-{ "took" : 7, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "school", "_type" : "school", "_id" : "5", "_score" : 1.0, "_source" : { "name" : "Central School", "description" : "CBSE Affiliation", "street" : "Nagan", "city" : "paprola", "state" : "HP", "zip" : "176115", "location" : [ 31.8955385, 76.8380405 ], "fees" : 2200, "tags" : [ "Senior Secondary", "beautiful campus" ], "rating" : "3.3" } }, { "_index" : "school", "_type" : "school", "_id" : "4", "_score" : 1.0, "_source" : { "name" : "City Best School", "description" : "ICSE", "street" : "West End", "city" : "Meerut", "state" : "UP", "zip" : "250002", "location" : [ 28.9926174, 77.692485 ], "fees" : 3500, "tags" : [ "fully computerized" ], "rating" : "4.5" } } ] } } -
全文查询
这些查询用于搜索全文，例如章节或新闻文章。该查询根据与该特定索引或文档相关联的分析器工作。在本节中，我们将讨论全文查询的不同类型。匹配查询此查询将文本或短语与一个或多个字段的值匹配。POST /school*/_search { "query":{ "match" : { "rating":"4.5" } } }运行上面的代码后，我们得到如下所示的响应：{ "took" : 44, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 0.47000363, "hits" : [ { "_index" : "school", "_type" : "school", "_id" : "4", "_score" : 0.47000363, "_source" : { "name" : "City Best School", "description" : "ICSE", "street" : "West End", "city" : "Meerut", "state" : "UP", "zip" : "250002", "location" : [ 28.9926174, 77.692485 ], "fees" : 3500, "tags" : [ "fully computerized" ], "rating" : "4.5" } } ] } } -
多个匹配查询
此查询将文本或短语与多个字段匹配。POST /school*/_search { "query":{ "multi_match" : { "query": "paprola", "fields": [ "city", "state" ] } } }运行上面的代码后，我们得到如下所示的响应：{ "took" : 12, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 0.9808292, "hits" : [ { "_index" : "school", "_type" : "school", "_id" : "5", "_score" : 0.9808292, "_source" : { "name" : "Central School", "description" : "CBSE Affiliation", "street" : "Nagan", "city" : "paprola", "state" : "HP", "zip" : "176115", "location" : [ 31.8955385, 76.8380405 ], "fees" : 2200, "tags" : [ "Senior Secondary", "beautiful campus" ], "rating" : "3.3" } } ] } } -
查询字符串查询
该查询使用查询解析器和query_string关键字。POST /school*/_search { "query":{ "query_string":{ "query":"beautiful" } } }运行上面的代码后，我们得到如下所示的响应：{ "took": 16, "timed_out": false, "_shards": { "total": 1, "successful": 1, "skipped": 0, "failed": 0 }, "hits": { "total": { "value": 1, "relation": "eq" }, "max_score": 1.1374959, "hits": [ { "_index": "school", "_type": "_doc", "_id": "5", "_score": 1.1374959, "_source": { "name": "Central School", "description": "CBSE Affiliation", "street": "Nagan", "city": "paprola", "state": "HP", "zip": "176115", "location": [ 31.8955385, 76.8380405 ], "fees": 2200, "tags": [ "Senior Secondary", "beautiful campus" ], "rating": "3.3" } } ] } } -
词级查询
这些查询主要处理结构化数据，例如数字，日期和枚举。POST /school*/_search { "query":{ "term":{"zip":"176115"} } }运行上面的代码后，我们得到如下所示的响应：…………………………….. hits" : [ { "_index" : "school", "_type" : "school", "_id" : "5", "_score" : 0.9808292, "_source" : { "name" : "Central School", "description" : "CBSE Affiliation", "street" : "Nagan", "city" : "paprola", "state" : "HP", "zip" : "176115", "location" : [ 31.8955385, 76.8380405 ], } } ] ………………………………………….. -
范围查询
该查询用于查找具有给定值范围之间的值的对象。为此，我们需要使用运算符，例如-- gte - 大于等于
- gt - 大于
- lte - 小于等于
- lt - 小于
例如，观察下面给出的代码-POST /school*/_search { "query":{ "range":{ "rating":{ "gte":3.5 } } } }运行上面的代码后，我们得到如下所示的响应：{ "took" : 24, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "school", "_type" : "school", "_id" : "4", "_score" : 1.0, "_source" : { "name" : "City Best School", "description" : "ICSE", "street" : "West End", "city" : "Meerut", "state" : "UP", "zip" : "250002", "location" : [ 28.9926174, 77.692485 ], "fees" : 3500, "tags" : [ "fully computerized" ], "rating" : "4.5" } } ] } }还存在其他类型的术语级别查询，例如-- 存在查询 - 如果某个字段具有非null值。
- 缺少查询 - 这与存在查询完全相反，该查询搜索没有特定字段或字段值为空的对象。
- 通配符或正则表达式查询 - 此查询使用正则表达式在对象中查找模式。
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复合查询
这些查询是不同查询的集合，这些查询通过使用布尔运算符（例如and/or，或not）或针对不同的索引或具有函数调用等彼此合并。POST /school/_search { "query": { "bool" : { "must" : { "term" : { "state" : "Delhi" } }, "filter": { "term" : { "fees" : 2200 } }, "minimum_should_match" : 1, "boost" : 1.0 } } }运行上面的代码后，我们得到如下所示的响应：{ "took" : 6, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 0, "relation" : "eq" }, "max_score" : null, "hits" : [ ] } } -
地理查询
这些查询处理地理位置和地理位置。这些查询有助于找出学校或任何其他地理位置附近的地理对象。您需要使用地理位置数据类型。PUT /geo_example { "mappings": { "properties": { "location": { "type": "geo_shape" } } } }运行上面的代码后，我们得到如下所示的响应：{ "acknowledged" : true, "shards_acknowledged" : true, "index" : "geo_example" }现在，我们将数据发布到上面创建的索引中。POST /geo_example/_doc?refresh { "name": "Chapter One, London, UK", "location": { "type": "point", "coordinates": [11.660544, 57.800286] } }运行上面的代码后，我们得到如下所示的响应：{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ "_index" : "geo_example", "_type" : "_doc", "_id" : "hASWZ2oBbkdGzVfiXHKD", "_score" : 1.0, "_source" : { "name" : "Chapter One, London, UK", "location" : { "type" : "point", "coordinates" : [ 11.660544, 57.800286 ] } } } }